<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>01_JS的三种引入方式</title>
    <script src="01.js"></script>
</head>
<body>
    <button onclick="alert('请先登录！')">点击即玩</button>
    <button onclick="console.log('hello world')">点我</button>
    <h1 id="aaa">我是h1标题</h1>
    <script>
        console.log('我是内部js,我被执行了');
        console.log(aaa);
    </script>

</body>
</html>